People send their kids off glad to get rid of them for the day expecting teachers to just saw off the top of their heads and program their brains magically. They don't want to work for their education, they want it handed down like the rest of the free stuff that they get.
Teachers are not allowed to hold students back a grade anymore (or at least it takes an act of congress or something.) because it makes the school look bad. They cannot reward the better performing students. We have to keep the violent and disruptive kids in school because it is their "right" to an education.
I say: flush public education. Cut the school taxes (probably have to cut some other things in there too, but work it out people) so that people can pay for private education. And you know what? If the student chooses not to perform, they won't get the grade there. If they disrupt another paying student, then the disrupting student gets expelled. OMG! Accountability! The wonders of a little accountability!